A ferrofluid generally comprises a liquid which becomes magnetized in a presence of a magnetic field. Ferrofluids are generally a colloidal mixture of ferromagnetic or ferrimagnetic particles suspended in a carrier fluid. The carrier fluid may comprise, without limitation, an organic solvent, water, or other suitable fluid. Particles of the ferrofluid may be coated with a surfactant coating the particles to inhibit clumping. Ferrofluids may be manipulated by magnetic fields, but generally do not retain magnetization absent a magnetic field.